Recently, umbilical cord blood--the blood left in the umbilical cord and placenta after birth--has been recognized as a life-saving substance. The reason is that umbilical cord blood, like bone marrow, contains regenerative "stem" cells. Stem cells are the primitive cells from which other blood cells--white cells, red cells, and platelets--develop. Thus, they are the building blocks of the immune and blood cell systems. Cord blood stem cells are unique in that they are immature "naive" immune cells. When they are used in transplantation, they have reduced reactivity and are less likely to recognize the recipient as foreign. When transplanted into a sick person, even a single stem cell has the ability to regenerate the person's blood system. For this reason, stem cells are vital when a person's immune system has been weakened by radiation or chemotherapy, or by diseases that attack the immune system. Stem cells are highly effective against many diseases.
Since the potential of the stem cells in bone marrow has been recognized, about four thousand deaths per year are being prevented by bone marrow transplants. However, bone marrow is in short supply; the shortage of bone marrow amounts to 10,000-15,000 transplants per year that cannot be performed. As cord blood also contains regenerative "stem" cells, it is being used as an alternative to bone marrow. The number of cord blood transplants increased tenfold between 1994 and 1995. Many lives could be saved if umbilical cord blood were routinely banked and its additional stem cells became available for transplants.
Moreover, cord blood is much more effective than bone marrow for several reasons:
(1) It is less likely to trigger an adverse reaction when transplanted. The incidence of GVHD (Graft versus Host Disease) is about five times lower with cord blood as compared to bone marrow when the donor and recipient are unrelated (up to 90% GVHD for marrow, less than 20% with cord blood). When the donor and recipient are siblings, the rate of GVHD is ten times lower (2% for cord blood as compared to 20% for marrow). The engraftment rate for cord blood transplants is 85% overall.
(2) Cord blood stem cells are 8 to 11 times more "prolific" than bone marrow cells, and so better regenerate the body's blood system.
(3) Cord blood stem cells are better for gene herapies.
(4) No invasive procedures are needed to obtain ord blood.
(5) Cord blood is less likely to contain viruses than is bone marrow from adult donors, who have had a lifetime to acquire diseases.
Adults as well as children have been successfully treated with cord blood, and cord blood can be cryo-preserved in liquid nitrogen and remain usable for years. If a child's cord blood is preserved in this way, the grown individual can use his or her own stem cells later in life to fight various serious diseases. After age two, an individual's own cord blood is the most effective transplant material since it is less likely to be rejected than another individuals.
Cord blood is effective against numerous genetic and blood diseases and has the potential to become a valuable treatment for many others. Diseases which are now treatable with cord blood include: malignancies (leukemia, myeloma, and neuroblastoma); aplastic anemia; XKP; SCIDS; Wiskott-Aldrich Syndrome; thalessemia; Fanconi anemia; plasma cell disorders and inherited erythrocyte abnormities. At present, the majority of cord blood transplants are used to treat leukemia. Research is now under way on using cord blood to combat rheumatoid arthritis, AIDS, multiple sclerosis, sickle cell anemia, cancer of the lung and colon, and Hodgkin's lymphoma.
The International Cord Blood Foundation is promoting conservation and banking of cord blood. It is expected that greater awareness by physicians and expectant parents will increase the amount of retrieved cord blood and the number of lives saved. The National Institutes of Health, too, is spending millions of dollars to promote cord blood use.
However, the technology for extracting cord blood presents obstacles and obstructs the rapid acceptance of routinely banking all cord blood. The main problems are in (1) the convenience of collecting the blood and (2) obtaining an adequate amount of blood for both testing and banking.
Because there are so many uses for banked cord blood, because some therapies require large amounts, and because the cost of transporting and storing larger amounts as compared to smaller amounts is minimal, it is clear that the maximum possible amount of cord blood should be collected and stored. However, as will be seen from the discussion below, the present methods do not get all the available blood out of the umbilical cord.
The present standard delivery room protocol includes collecting and sending a small sample of umbilical cord blood to the laboratory shortly after delivery of the fetus for a variety of tests, including, but not limited to, hemoglobin, hematocrit, blood type and Rh factor, and antibody tests. Other laboratory studies on the cord blood specimen that could be performed include blood chemistries, blood cultures, HIV testing, testing for use of illegal drugs, such as cocaine, by the mother, lactate levels, blood gases such as oxygen and arbon dioxide saturation levels, and other studies.
Historically, this has been accomplished by attempting to direct a cord blood stream into opened laboratory test tubes and then capping the test tubes. Usually, spillage of cord blood occurs during this procedure, which is difficult for one person to perform.
The blood spillage is doubly bad because it not only wastes the precious blood but also increases the health workers' exposure to a potential HIV hazard. To decrease the amount of spilled blood, a funnel might be provided. However, to support a funnel and a test tube having a stopper while dripping blood would be even more awkward than merely filling a test tube. The used funnel would be another piece of contaminated trash. The test tube also ends up as contaminated trash and, if made of glass, it presents a puncture hazard in the event of breakage.
After a test tube or test tubes are filled with the desired amounts of blood and taken away, the attending pediatricians frequently call for a laboratory technician to come to the delivery room or newborn nursery soon after the birth to perform additional venipunctures or heel sticks on the newborn infant to obtain more blood samples for base line studies about the condition of the infant. These additional intrusions could of course be avoided by performing the same tests on cord blood, if more were available. However, the test tubes are gone by that time.
To collect larger amounts of cord blood for later tests or for long term preservation, the primitive and messy method of dripping blood into test tubes is too inefficient. At the present time bulk umbilical cord blood collection is performed mainly by using 50 cc syringes that contain a heparinized solution. The syringes are sent to pregnant women in the form of a kit. The expectant mother or parents are then responsible for bringing the kit to their delivery. The syringes, with needles attached, are given to the delivering doctor.
After delivery of the infant and cutting and clamping the cord the physician inserts the needle into the distal umbilical cord vein and slowly aspirates all available cord blood into the syringes. These syringes are then labeled for identification, needles are removed, the ends are capped, and they are placed into a zipper-locking plastic bag or bags. The bag is placed into an insulated mailing box, and they are mailed to a central processing laboratory. The syringes must be kept at room temperature through these steps.
This method requires a long time (about five minutes) and a substantial amount of effort. Three or four syringes are used (each being capped, labeled, etc.) and the needles must be inserted at numerous places along the cord for best results; each insertion site must be swabbed prior to sticking with the needle. Literature on this method (Cbr Collection Kit brochure) teaches against any manipulation of the umbilical cord; the cord is laid out on a tray and the needles stuck in a various places in an attempt to collect sufficient blood. The average amount collected is 80 cc of cord blood.
The yield is low because, first, blood is drawn only from the single umbilical cord vein, and not from either of the two arteries, and second, because the collection efficiency of applied suction is low (as is discussed further below)
Besides the large amounts of time and effort required, and the low yield, this method of collecting cord blood is dangerous because of the several needles that need to be uncovered, used, removed, and disposed of, and the because of the numerous sticks into the thin-walled umbilical vein of the slippery cord. The syringes, tray, and needles constitute a great deal of hazardous waste material and/or extra cleaning and sterilizing work.
A different sort of prior-art collection apparatus is disclosed by Eder et al, in U.S. Pat. No. 5,342,328 and in an article in Obstetrics and Gynecology. Their "umbilicup" device, made by MKMI of Encino, Calif., is a rigid cylindrical container with a removable top lid and a funnel-shaped interior baffle. The umbilical cord is cut at both ends and placed into the container, which includes a guarded needle communicating with, and extending downward from, the container. The rubber stopper of an evacuated test tube is forced onto the needle, and the vacuum draws off blood pooled in the funnel-shaped bottom of the container.
The umbilicup avoids the use of uncovered needles, but has numerous drawbacks; the greatest is that the collection efficiency of the umbilicup is quite low. The cord is merely piled into the container, and blood drips into the bottom. Blood in the many looped parts of the cord is trapped, never reaches the bottom of the container, and never is collected. The amount of blood the umbilicup collects from an entire cord is only 6.1 cc (mean)+/-3.1 cc (one standard deviation), with about 2 more cc if heparin is added; in other words, a maximum of about 11 cc. In some cases the umbilicup collects less than one cc of blood, and the collected blood can be as little as 0.4 cc. Without the addition of heparin, there is insufficient blood for testing in almost 3% of uses.
Like syringes, the umbilicup is relatively expensive and creates bulky contaminated plastic waste and dirty needles. While faster than the painstaking needle suction method, the use of the umbilicup still requires additional handling and table space and time must be allowed for the blood to drip into the bottom of the container. As with the primitive drip method, the test tubes can present a puncture hazard if made of glass.
Another disadvantage of the umbilicup is that the pooled blood contacts the outside of the cord, which is more likely to be contaminated than the inside of the cord. Thus, the risk of the collected cord blood being contaminated is greater.